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Aphids on poplar and aspen

Blackman & Eastop list about 120 species of aphids  as feeding on poplars worldwide, and provides formal identification keys for aphids on Populus (poplar and aspen). Some species only feed on one species of Populus, but many feed on several related species. Some are free-living, whilst other form galls or leaf nests.

The species below are those we have found most frequently, listed in rough order of abundance. For assistance on distinguishing poplar and aspen see below. 

 

Chaitophorus populeti (Poplar shoot aphid)

Adult Chaitophorus populeti apterae are oval, shiny dark green to black. There is sometimes a paler stripe along the midline of the thorax and the front of the abdomen. There are separate bands on the pre- and mesonotum and abdominal tergites 7-8. The antennae are more than half the length of the body. The terminal process is about twice the length of the base of the last antennal segment. The siphunculi are dark. The body length of Chaitophorus populeti is 1.5-2.9 mm.

 

Chaitophorus populeti alates (see second picture above) are dark green to black with broad brown dorsal abdominal cross-bands and marginal plates. The wing veins are brown-shadowed.

The poplar shoot aphid lives on the young shoots and terminal leaf petioles of various poplar (Populus) species, especially of the aspen (Populus tremula) and white poplar (Populus alba). It is usually attended by ants. Oviparae and males occur in October-November. Chaitophorus populeti is found throughout the Palaearctic region.

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Chaitophorus populialbae (Poplar leaf aphid)

Adult Chaitophorus populialbae apterae are small, short-bodied, oval, greenish to yellowish white, often with small green spots (see first picture below). The head and tips of antennal segments and tarsi are light brown. The antennae are 0.6-0.9 times the length of the body, and the terminal process is 1.7-3.3 times as long as the base of the last antennal segment. The siphunculi are pale. The body length of Chaitophorus populialbae is 1.0-2.3 mm.

 

The alate (see second picture above) has the head, thorax and antennae black, and the abdomen green with dark brown cross-bands, often with bands coalescing on abdominal tergites 2-6. .

Poplar leaf aphids live in (usually) small colonies on undersides of leaves of various Poplars (Populus spp.) and are sometimes ant-attended. Oviparae and males occur in September-November. Chaitophorus populialbae occur throughout the Palaearctic region, parts of Africa, and are introduced and widespread in North America.

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Chaitophorus leucomelas (Poplar leaf aphid)

Adult apterae of Chaitophorus leucomelas are elongate oval in shape and vary from green to yellow. The dark dorsal markings are rather variable. The adults usually have two dark stripes along the sides (sometimes divided segmentally) which tend to merge on the fifth abdominal tergites as can be seen in the first picture below. Alternatively the stripes may be missing. Whatever the pattern there are (nearly) always broad pale spinal and marginal areas. The antennae are half as long as the body of the aphid, with the terminal process of the sixth antennal segment 2.7-3.3 times the base of that segment. The short truncate siphunculi are dark at least apically. The cauda is rounded and very pale. The body length of Chaitophorus leucomelas ranges from 1.2 to 2.4 mm.

 

Chaitophorus leucomelas alates have dark brown dorsal abdominal cross-bands and separate marginal sclerites visible in the second image above.

The host plant of Chaitophorus leucomelas in Europe is mainly black poplar (Populus nigra) and related species and hybrids, but in North America a wider range of species is colonised. They feed on young shoots of Populus spp. in spring, and later under leaves, in leaves stuck together by moth larvae, or in leaf galls vacated by other insects. It is commonly ant-attended. Chaitophorus leucomelas is widely distributed in Europe, North Africa and Asia, and has been introduced to South Africa and North and South America.

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Chaitophorus tremulae (Aspen leaf aphid)

Chaitophorus tremulae apterae are elongate oval with the dorsum solidly blackish sclerotic, rather densely sculptured with denticular spinules, and very often with a paler line along the mid-dorsum (see first picture below). Except in the fundatrix, abdominal tergite 1 is more or less completely fused with the carapace on tergites 2-6. The antennae are usually dark and half the length of the body, and the terminal process is 2.1-2.8 times as long as the base of the last antennal segment. The siphunculi are dark and the legs are brown with the hind pair darker. The body length of Chaitophorus tremulae is 1.2-2.5 mm.

 

Alates have very broad black dorsal abdominal cross-bands which tend to coalesce. Immature Chaitophorus tremulae are bright green.

Aspen leaf aphids live in small colonies on undersides of leaves of Aspen (Populus tremula) and a few related species of Populus. They have also been found in leaves spun together by other insects, or in leaf-nest galls made by another group of aphids (Pemphiginae). Oviparae and alate males occur in October. Chaitophorus tremulae occurs throughout Europe and as subspecies in the Far East.

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Thecabius affinis (Poplar-buttercup gall aphid)

The Thecabius affinis fundatrix is green or bluish green, is covered in wax and lacks siphunculi. It inhabits a small gall of its own on poplar (Populus) formed by folding the edge of a leaf. Its offspring leave this gall in May-June and move to other galls on poplar formed by feeding on the midrib of a young leaf which induces the leaf lamina to fold along the midrib towards the underside (see first picture below). The outer, upper side of the leaf becomes blistered and yellowish or reddish.

 

Winged viviparous females (see second picture below) leave the gall on poplar in late June-July to found waxy colonies at the stem bases and on the runners of buttercups (Ranunculus). The winged viviparae female is greenish, covered with wax spicules and has siphuncular pores. The antennae are short, about half the body length. The terminal process is 0.25 times the length of the base of the last antennal segment. The body length of winged Thecabius affinis females is 2.2-3.1 mm.

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Pemphigus bursarius (Poplar-lettuce gall aphid)

In spring, aphids form yellowish or reddish pouch-shaped galls (see picture below) on the petioles of the leaves of poplar. There may be more than one gall per petiole and the leaf lamina may curl and yellow.

 

The developing fundatrix in the gall is green with brown head and legs, wax covered and has no siphunculi. The 4-segmented antennae are about 0.12-0.15 times the length of the body. The winged viviparae that emerge from these galls (see second picture above) are greyish-green or greyish-brown with small siphuncular pores and are lightly covered with wax powder. Their antennae are 0.33-0.4 times the length of the body and have a distinct terminal process. There is brown shadowing around the wing veins.

This species host alternates between poplar and members of the daisy family Asteraceae, especially lettuce. In summer they live on the roots of the secondary host. The picture below shows a developing alate living on the roots of lettuce. It can be a serious pest of lettuce. Its distribution is almost cosmopolitan being found in Europe, western and central Asia, the Americas, northern and southern Africa and (possibly) Australia and New Zealand.

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Pemphigus gairi (Poplar pouch gall aphid)

In spring aphids form yellowish or reddish pouch-shaped galls (see first picture below) on or near the midrib of the leaves of poplar, mainly black poplar (Populus nigra). The developing fundatrix in the gall is covered with wax. The fundatrix is green or greyish green and has no siphunculi. The 4-segmented antennae are about 0.12-0.15 times the length of the body.

 

The winged viviparae (see second picture above) emerge from these galls in summer through an opening on the underside of the leaf. They have a black head and pterothorax, small siphunculi and a rather elongate greenish wax-dusted abdomen. The fused terminal segments of the rostrum are 0.07-0.10 mm long, usually less than 0.55 the second hind tarsal segment. The third antennal segment is shorter than the combined length of fourth and fifth antennal segments.Apterae on secondary hosts are yellow-green with white wax wool.

This species host alternates between poplar and fool's parsley (Aethusa cynapium). In summer they live above ground on the secondary host, often in the inflorescences. Distributed throughout Europe and into Asia and north Africa.

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Pemphigus protospirae (Poplar spiral gall aphid)

In spring, aphids form green or green mottled with red smooth galls formed by thickening, flattening and spiral twisting of the leaf petiole of Populus nigra (see picture below) on the petioles of the leaves of poplar. The fundatrices have antennae about 0.2 × the length of the body and lack siphunculi.

 

All the second generation aphids are winged and leave during late spring to early summer. The winged migrants (see picture below left) are greyish-green and lightly covered with waxy powder. The antennae (see picture below right) are 0.33 - 0.40 times the length of the body. The most proximal rhinarium on third antennal segment is distal to the tooth. The number of secondary rhinaria on the third antennal segment is 10-143, on the fourth 2-5, on the fifth 2-4, and on the base of the sixth 2-8.

The winged migrants move to aquatic umbellifers (Apiaceae) as secondary hosts.

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Pterocomma populeum (Poplar bark999 aphid)

Pterocomma populeum apterae are yellowish grey or brownish with paired dark patches on at least the posterior abdominal tergites (see first picture below). There are intersegmental cross-bands of greyish white wax. The second antennal segment has 4-6 hairs (cf. Pterocomma tremulae  which has 8-12 hairs on that segment). Pterocomma populeum siphunculi are pale yellow and almost cylindrical with hardly any swelling. The body length is 2.7-4.5 mm.

 

Pterocomma populeum alates have broad dark dorsal abdominal bands (see second picture above).

The poplar bark aphid feeds on branches, or two year old twigs, of many poplar (Populus) species. Oviparae and alate males may be found in October to November. The species is nearly always ant attended. It is widespread in Europe and has been recorded from North Africa and parts of Asia. Pterocomma populeum has been introduced to North and South America.

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Pachypappa tremulae (Aspen-spruce aphid)

In springtime Pachypappa tremulae fundatrices (not shown here) may be found on the twigs of aspen (Populus tremula. They are unusually large (body length 5.0-6.6 mm) and are almost globular. They are a dirty reddish or yellowish brown colour, but appear silvery as they are covered with long fine hairs. They have no siphuncular pores and do not secrete any wax. The offspring of the fundatrix move on to the new shoots and form a rosette like leaf nest (see first picture below) formed by bending of the leaf petioles and stunting of growth of the shoot.

 

Guest images copyright Volker Fäßler,  all rights reserved

These offspring all develop to winged individuals (see second picture above) which are orange or reddish brown, covered in wax and with very small siphuncular pores. They migrate in June to form colonies on the roots of spruce (Picea abies). Pachypappa tremulae apterae on spruce are pale yellowish white with tufts of wax posteriorly. Sexual forms then return to aspen in autumn. Pachypappa tremulae is widely distributed in the northern palaearctic, east to China and Japan.

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Species of poplar and aspen

The European aspen (Populus tremula) is a deciduous tree native to cool temperate parts of Europe and Asia. The leaves (see pictures below) are nearly round, slightly wider than long, 2-8 cm in diameter with a coarsely toothed margin and a laterally flattened petiole.

 

White poplar (Populus alba) is a medium-sized deciduous tree native from Europe through to central Asia. The leaves (first picture below) are five lobed, 4-15 cm long with a thick covering of white down the underside and when young on the upper side as well. The hybrid with aspen is known as grey poplar (Populus × canescens) and has intermediate characteristics. Black poplar (Populus nigra) has 3-4 different subspecies and a common cultivar - the Lombardy poplar - which has a very narrow crown. The leaves (second picture below) are diamond shaped to triangular, 5-8 cm long and 6-8 cm broad, and green on both surfaces.

 

Feedback & comments

  • Willem N. Ellis, June 10, 2014

    I just discovered this pdf  on the web; you may find it interesting.

    But it also points to an error (I think!) in your site, in 'aphids on poplar'. The picture of Pemphigus protospirae actually is spyrothecae, compact as it is. This also better fits the terse description by Blackman & Eastop.

  • Bob Dransfield, InfluentialPoints.com  June 10

    Many thanks for the Osdiadacz paper along with your comments on ID of the spiral poplar gall.

    We initially identified it as Pemphigus spyrothecae based on the characteristics of the gall. However, we then examined an alate under the microscope and, using Blackman & Eastop's key (and Dixon's key), it came out instead to Pemphigus protospirae. Frustrating!

    Unfortunately we only had one alate to check, and repeated examination did not do the aphid much good (we looked at it in alcohol as we do not have facilities to prepare permanent mounts).

    We were hoping for more this year to try again, but unfortunately none yet.

Acknowledgements

We have made provisional identifications from high resolution photos of living specimens, along with host plant identity. In the great majority of cases, identifications have been confirmed by microscopic examination of preserved specimens. We have used the keys and species accounts of Blackman & Eastop (1994)  and Blackman & Eastop (2006)  supplemented with Blackman (1974) , Stroyan (1977) , Stroyan (1984) , Blackman & Eastop (1984) , Heie (1980-1995) , Dixon & Thieme (2007)  and Blackman (2010) . We fully acknowledge these authors as the source for the (summarized) taxonomic information we have presented. Any errors in identification or information are ours alone, and we would be very grateful for any corrections. For assistance on the terms used for aphid morphology we suggest the figure  provided by Blackman & Eastop (2006).

Useful weblinks 

References

  •  Blackman, R.L. & Eastop, V.F. Aphids on the world's plants An online identification and information guide. Full text